1. Technical Field
The present invention relates to a nanoprint transfer method for forming a fine structure on a substrate using a mold comprising a heating and a pressure-applying mechanism.
2. Background Art
In recent years, the semiconductor integrated circuits are becoming increasingly finer and more integrated. To cope with such size reductions and increased levels of integration, the accuracy of photolithography equipment as a pattern transfer technology has been continuously improved. However, the processing method now involves a scale close to that of the wavelength of the photolithographic light source, and the lithography technology is close to its limit. As a result, in order to allow for further reductions in size and achieve higher accuracy, electron beam lithography equipment, which is a type of charged-particle beam equipment, has come to be used more often than photolithography technology.
When patterns are formed using an electron beam, a mask pattern is drawn, in contrast to the one-shot exposure method whereby an i-line or excimer laser light source is used for pattern formation. Accordingly, the electron beam pattern forming method takes more time for exposure (drawing) as the number of patterns to be drawn increases, disadvantageously resulting in increased time for pattern formation. As the level of integration greatly increases from 256 M to 1 G to 4 G, the time required for pattern formation also increases greatly, possibly resulting in significantly lowered throughput. Thus, in order to reduce time required by the electron beam lithography equipment, development of a one-shot pattern irradiation method is underway whereby masks of various shapes are combined and are irradiated with an electron beam in a single shot and electron beams of complex shapes are formed. While this allows ever finer patterns to be obtained, it also results in an increase in the size of the electron beam lithography equipment, and it requires a mechanism for controlling mask positions more accurately, thereby increasing equipment cost.
Technologies for carrying out fine pattern formation at low cost are disclosed in U.S. Pat. No. 5,259,926, U.S. Pat. No. 5,772,905 and S. Y. Chou et al., Appl. Phys. Lett., vol. 67, p. 3314 (1995), for example. According to these technologies, a mold having the same concave-convex pattern as that which is desired to be formed on a substrate is stamped onto a resist film layer formed on the surface of the substrate, thereby transferring the predetermined pattern onto the substrate. Particularly, it is described in U.S. Pat. No. 5,772,905 and S. Y. Chou et al., Appl. Phys. Lett., vol. 67, p. 3314 (1995) that the disclosed nanoimprint technique, using a silicon wafer as a mold, can transfer and form fine structures of not more than 25 nanometers.
JP Patent Publication (Kokai) No. 2002-283354 discloses a mold for an imprining process, the mold being capable of correct transfer of patterns by a press operation and being covered with perfluoropolyether having a functional group that chemically reacts with the material of the mold. The object of this prior art is the manufacture of an imprint-process mold having a good releasing property with respect to a polymeric resin and in which a mold-releasing agent does not exist in the concave grooves in the mold, without releasing toxic gases into the atmosphere. Specifically, the publication discloses a method of manufacturing the imprint-process mold comprising a first step of washing the surface of the imprint-process mold, and a second step of exposing the imprint-process mold to the aforementioned perfluoropolyether.